R.Manasseh Fluid Dyn Papers
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The aircraft was a Cessna 340A (VH-EOS) operated by the Flinders Institute for
Atmospheric and Marine Sciences (FIAMS). It is equipped with several sensors in
addition to standard aircraft and meteorological instrumentation, of which
the following are pertinent to the present note. A five-hole nose-cone
pressure-port air motion sensing system in combination with a ring-laser
Inertial Navigation System (INS) and a Global Positioning System (GPS)
receiver enables accurate measurements of the three-dimensional wind vector.
Two air-chemistry instruments measured concentrations of pollutant indicators
and 
. At the time of writing, only the raw data from
these instruments have been made available; hence, these data will be used
qualitatively in this paper. A forward-looking video camera was used to
monitor the cloud cover, visibility and other visual features along the
flight path.
The signals from the analogue sensors were simultaneously sampled at 2 Hz and 10 Hz. Digital data from the GPS receiver was available once per second, while the data from the INS was available at various rates, depending on the channel, between twice and 50 times per second. The data acquisition system incorporates real-time data processing and viewing facilities, enabling in-flight decisions to be made on the flight strategy. The FIAMS software package RAMF was used to process and display the data as presented below.
Figure 1 shows the metropolitan area with
landmarks below points where major course changes were made during the flight.
The flight strategy was broadly based on a traingular circuit of three `legs',
forming a triangle as shown in schematic form on
figure 1, although significant variations
from this were often made if particularly interesting phenomena were being
tracked or if air-traffic control required a deviation. For clarity in the
following descriptions, various legs may be segmented into `runs'. On the day
of interest, 16 March 1994, there were three circuits. The basic circuit
contains the following elements. The first leg goes from point `S', which is
over the ocean to the south-east of Sydney Airport, inland along the Georges
River to Warragamba Dam. This southern leg is at low level, typically
150-200 m. At Warragamba Dam a `sounding' is made with the aircraft, involving
an ascent to 2000 m and a return to about 200 m. Next, the northern leg goes
from Warragamba Dam to Newport Beach at 200-300 m. A second sounding can be
made offshore at Newport Beach. The final, ocean leg runs southwards over the
ocean to point `S' and can include segments down to 60 m. Typical flying speeds
were 
.
Figure 1: The Sydney metropolitan area. Landmarks indicate where major course
changes were made during the flight and identify places referred to in the text.
Sea-level measurements were made from a 10 m `Cavalier'-type sailing yacht
which was fitted with an anemometer and temperature instrumentation. The
vessel's true velocity was also logged, enabling the local wind speed to be
calculated. In addition, an aircraft-type altimeter was used to record
variations in atmospheric pressure. The yacht sailed approximately east from
Sydney Harbour to a point about 35 km from shore at roughly 
,
then returned on the same track. The aircraft circuits occurred while the yacht
was making measurements.
R.Manasseh Fluid Dyn Papers
R.Manasseh Fluid Dyn Home